Further to my last thought…..
Are you driving the control grid with a DC or pulsed signal? If not DC, could there be a strobe effect between your high voltage and the control signal? Bill From: neonixie-l@googlegroups.com [mailto:neonixie-l@googlegroups.com] On Behalf Of peter bunge Sent: Friday, February 12, 2021 8:14 AM To: neonixie-l@googlegroups.com Subject: Re: [neonixie-l] 8453/Z550M erratic Hi Martin, I changed the circuit back to halfwave using a single diode from the bridge rectifier and changing the capacitor. This was absolute minimum change without moving anything else. Back came the erratic flashing. So it's not the diode. It just does not like half wave. My circuits are direct copies from the data sheet. Peter On Thu, Feb 11, 2021 at 5:21 PM Dekatron42 <martin.forsb...@gmail.com <mailto:martin.forsb...@gmail.com> > wrote: Nice that it works! My understanding is that they need rectified AC, with just a little smoothing so as not to make it a pure DC voltage, as they extinguish during the portion of the voltage when it is to low to maintain the glow, and they are re-ignited when the voltage rise again as long as a trigger electrode has the correct voltage to initiate a glow, much like a thyratron. Maybe you can find the reason for it working now compared to earlier failures if you check the voltage across the Anode-Cathode-Ignition electrode with an oscilloscope? I've also had some problems with CMOS ic's when I have had poor, or no, connection to VCC/GND on the power pins - the circuit worked quite well until I touched some pins. /Martin On Thursday, 11 February 2021 at 21:50:49 UTC+1 bung...@gmail.com <mailto:bung...@gmail.com> wrote: I have solved the problem but I don't understand why. Having tried all the suggestions except this, I went to a full wave rectifier. It is not quite the same as the data sheet but does the same thing. It also has the capacitor connected per the data sheet, the same as my half wave circuit that did not work. This is rock solid with no indication of any other flickering. I am using the first (worst) tube. Touching the glass has no effect. Apparently the tube does not like half wave. Perhaps it was my 1N4007 diode? They can switch too fast and maybe it needed a snubber. I also tried DC from a variable regulated power supply (HP 6448B up to 600 volt@1.5 <mailto:volt@1.5> amp, and no, I did not go that far). That locked the display on one digit. The data sheet says it needs rectified line, not DC. I am running my tests from an HP supply for the 5v and an isolation transformer driven by a Variac for the AC so I have full control of all voltages. This is my final schematic. It is driven by a PIC with parallel connectors for each display. I used a PIC to generate the BCD because CMOS would not drive the three 74141 for the Nixies. The PIC counts up and down at varying speeds which would have been more difficult with CMOS. <https://groups.google.com/group/neonixie-l/attach/4ca4d15a6b39c/8453%20Circuit.jpg?part=0.1&view=1> On Thu, Feb 11, 2021 at 10:33 AM Dekatron42 <martin....@gmail.com <mailto:martin....@gmail.com> > wrote: Touching the glass means that you get a capacitive coupling which will upset them somewhat, there was a special socket made for this by Philips which has a partial metal screen surrounding the tube. The socket is nicknamed "der Kuss" , "The kiss", due to its form. I couldn't find a photo on the Internet now but I know it exists as I have some in my storage and in an instrument that uses them. That instrument is called PW4261 Timer, some photos of the externals can be found on the Internet. On this socket all of the resistors are mounted flush to the pins to minimize the distance, but the capacitors and power supply is mounted some 40cm from the tubes themselves, likewise there are long wires to the drivers. You can also have a look at the manual for the PW4231 which I scanned that can be downloaded from here: https://frank.pocnet.net/other/sos/Philips_PW4232.pdf if that can help you with the voltages for the drivers. /Martin On Thursday, 11 February 2021 at 15:50:55 UTC+1 bung...@gmail.com <mailto:bung...@gmail.com> wrote: I meant dekatron in my last reply to gregebert. I have 3 of these tubes, all apparently new (NOS). Per your suggestion I tried the other two. One is almost perfect but flashes the 2 a bit when 8 is selected. The third is perfect unless I hold the tube in my fingers by the glass where I get lots of random flashing. Remember that the really bad one works perfectly with the capacitor moved as I mentioned. I don't know if touching the glass affects it. More later, I will be away this morning. Peter. On Thu, Feb 11, 2021 at 2:10 AM Dekatron42 <martin....@gmail.com <mailto:martin....@gmail.com> > wrote: Have you tried the circuit in the J.B Dance book below? Here they use a center tapped transformer and also a much lower value capacitor, only 33nF versus 250nF in your circuit - I've only evere seen 33nF used in real instruments using these indicators. Quite a few of the Z550M/ZM1050 are broken internally, I have a box of them, and that seems to be due to the welding of the internal parts coming loose when shaken or hit hard (the same problem exists with the B9012/NL9012 tubes - I have a few broken ones of those too with internal pieces that have come loose) - sometimes you can hear these loose pieces if you shake the tube very carefully close to your ear. What usually happens is that a rather large round center piece comes loose and in the worst case shortens some of the electrodes but usually only makes it hard or impossible to get all digits to light up poperly and some of them trigger easier than others due to the distances between electrodes are differing, shaking the tube a little moves that effect around so other digits will start to work and vice versa. /Martin <https://groups.google.com/group/neonixie-l/attach/4b6a9194d49d6/JBDance-Z550M.JPG?part=0.1&view=1> On Thursday, 11 February 2021 at 06:02:24 UTC+1 gregebert wrote: If you have an isolation transformer, can you put a scope on the cathode line to verify the ripple is not excessive ? Rk and Ck create an RC filter around 77Hz, and the line is 50-60Hz, so there could be some ripple. On Wednesday, February 10, 2021 at 8:26:51 PM UTC-8 bung...@gmail.com <mailto:bung...@gmail.com> wrote: I tried varying it with absolutely no effect. It runs perfectly at 5v with the capacitor moved to the other side of the resistor. However I was clocking slowly. It may not run at spec speed. I seem to remember reading of using 5 to 8 volts for the logic. The data sheet shows the following which I'm inclined to believe. I will try Ck directly on the pins tomorrow. Someone must have tried this circuit. <https://groups.google.com/group/neonixie-l/attach/4949b0494c68d/8453%20Cct.JPG?part=0.1&view=1> On Wed, Feb 10, 2021 at 11:12 PM gregebert <greg...@hotmail.com <mailto:greg...@hotmail.com> > wrote: I suspect the differential voltage between lit vs non-lit numerals is too low. The CMOS device is basically driving grids to determine which cathode will be illuminated. I've seen similar behavior with an A-101 dekatron. What voltage are you using for VDD ? Is it 8V as indicated on the schematic, or a more-conventional 5V ? On Wednesday, February 10, 2021 at 7:22:25 PM UTC-8 bung...@gmail.com <mailto:bung...@gmail.com> wrote: I think you are wrong. The literature explains this tube is designed to be driven by 5v logic and it does work. The steering electrodes are close to the Anode voltage which is grounded and only 5v pulses (square waves) are needed. Note all the cathodes are connected together internally. I got to thinking about the C1 position. The data sheet shows it per my schematic and I can't believe they made that mistake several times including the hand drawn notes of the designer. I think maybe I needed to have C1 directly on the socket pins and will try that tomorrow. Thanks for your interest though but you are thinking Nixie Tubes, this is a special tube with steering electrodes.. On Wed, Feb 10, 2021 at 9:42 PM chuckrr <chu...@all2easy.net <mailto:chu...@all2easy.net> > wrote: That schematic is so wrong in so many ways. You need high voltage transistors operating the tube cathodes. You need high resistance drving the transistor bases. You need a buffer such as 4049 or 4050 driving the resistor, which in turn drives the transistor base. Only then would I dare to use the 4028....to operate the buffer, which in turn operates the transistor base via appropriate high resistance. That is the only sure fire way I know of to attain noise-free performance from CMOS logic driving cold cathode tubes. That schematic there is a noisy deal. ---- Original Message ---- From: "peter bunge" <bung...@gmail.com <mailto:bung...@gmail.com> > Sent: 2/10/2021 8:15:21 PM To: "neonixie-l" <neoni...@googlegroups.com <mailto:neoni...@googlegroups.com> > Subject: [neonixie-l] 8453/Z550M erratic Using the schematic from the data sheet This works with the count moving around but other numbers flash erratically, especially close to the number that is supposed to be lit. When I moved the bottom of C1 to the other side of R1 it works perfectly. It is rock steady and does not care about line voltage or the 5v supply (shown above as 8v but used at 5v) If this is an error it is continued through all the documentation and is consistent. Changing the value of C1 up and down by 10 had little effect but a smaller C1 helps a bit. My Rst are all directly on the socket pins and the wires are all about 5 inches long. I have varied the line voltage with little effect. Any suggestions??? -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+...@googlegroups.com <mailto:neonixie-l+...@googlegroups.com> . 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